344 lines
12 KiB
Python
344 lines
12 KiB
Python
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from __future__ import absolute_import
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from __future__ import print_function
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import os
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import sys
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from io import BytesIO
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from io import DEFAULT_BUFFER_SIZE
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from io import FileIO
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from io import RawIOBase
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from io import UnsupportedOperation
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from gevent._compat import reraise
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from gevent._fileobjectcommon import cancel_wait_ex
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from gevent._fileobjectcommon import FileObjectBase
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from gevent._fileobjectcommon import OpenDescriptor
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from gevent._fileobjectcommon import WriteIsWriteallMixin
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from gevent._hub_primitives import wait_on_watcher
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from gevent.hub import get_hub
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from gevent.os import _read
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from gevent.os import _write
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from gevent.os import ignored_errors
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from gevent.os import make_nonblocking
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class GreenFileDescriptorIO(RawIOBase):
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# Internal, undocumented, class. All that's documented is that this
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# is a IOBase object. Constructor is private.
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# Note that RawIOBase has a __del__ method that calls
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# self.close(). (In C implementations like CPython, this is
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# the type's tp_dealloc slot; prior to Python 3, the object doesn't
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# appear to have a __del__ method, even though it functionally does)
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_read_watcher = None
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_write_watcher = None
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_closed = False
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_seekable = None
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_keep_alive = None # An object that needs to live as long as we do.
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def __init__(self, fileno, open_descriptor, closefd=True):
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RawIOBase.__init__(self)
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self._closefd = closefd
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self._fileno = fileno
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self.name = fileno
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self.mode = open_descriptor.fileio_mode
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make_nonblocking(fileno)
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readable = open_descriptor.can_read
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writable = open_descriptor.can_write
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self.hub = get_hub()
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io_watcher = self.hub.loop.io
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try:
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if readable:
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self._read_watcher = io_watcher(fileno, 1)
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if writable:
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self._write_watcher = io_watcher(fileno, 2)
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except:
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# If anything goes wrong, it's important to go ahead and
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# close these watchers *now*, especially under libuv, so
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# that they don't get eventually reclaimed by the garbage
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# collector at some random time, thanks to the C level
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# slot (even though we don't seem to have any actual references
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# at the Python level). Previously, if we didn't close now,
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# that random close in the future would cause issues if we had duplicated
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# the fileno (if a wrapping with statement had closed an open fileobject,
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# for example)
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# test__fileobject can show a failure if this doesn't happen
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# TRAVIS=true GEVENT_LOOP=libuv python -m gevent.tests.test__fileobject \
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# TestFileObjectPosix.test_seek TestFileObjectThread.test_bufsize_0
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self.close()
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raise
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def isatty(self):
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# TODO: Couldn't we just subclass FileIO?
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f = FileIO(self._fileno, 'r', False)
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try:
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return f.isatty()
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finally:
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f.close()
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def readable(self):
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return self._read_watcher is not None
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def writable(self):
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return self._write_watcher is not None
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def seekable(self):
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if self._seekable is None:
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try:
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os.lseek(self._fileno, 0, os.SEEK_CUR)
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except OSError:
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self._seekable = False
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else:
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self._seekable = True
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return self._seekable
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def fileno(self):
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return self._fileno
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@property
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def closed(self):
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return self._closed
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def __destroy_events(self):
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read_event = self._read_watcher
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write_event = self._write_watcher
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hub = self.hub
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self.hub = self._read_watcher = self._write_watcher = None
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hub.cancel_waits_close_and_then(
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(read_event, write_event),
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cancel_wait_ex,
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self.__finish_close,
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self._closefd,
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self._fileno,
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self._keep_alive
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)
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def close(self):
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if self._closed:
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return
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self.flush()
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# TODO: Can we use 'read_event is not None and write_event is
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# not None' to mean _closed?
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self._closed = True
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try:
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self.__destroy_events()
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finally:
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self._fileno = self._keep_alive = None
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@staticmethod
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def __finish_close(closefd, fileno, keep_alive):
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try:
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if closefd:
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os.close(fileno)
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finally:
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if hasattr(keep_alive, 'close'):
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keep_alive.close()
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# RawIOBase provides a 'read' method that will call readall() if
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# the `size` was missing or -1 and otherwise call readinto(). We
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# want to take advantage of this to avoid single byte reads when
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# possible. This is highlighted by a bug in BufferedIOReader that
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# calls read() in a loop when its readall() method is invoked;
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# this was fixed in Python 3.3, but we still need our workaround for 2.7. See
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# https://github.com/gevent/gevent/issues/675)
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def __read(self, n):
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if self._read_watcher is None:
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raise UnsupportedOperation('read')
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while 1:
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try:
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return _read(self._fileno, n)
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except OSError as ex:
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if ex.args[0] not in ignored_errors:
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raise
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wait_on_watcher(self._read_watcher, None, None, self.hub)
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def readall(self):
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ret = BytesIO()
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while True:
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try:
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data = self.__read(DEFAULT_BUFFER_SIZE)
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except cancel_wait_ex:
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# We were closed while reading. A buffered reader
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# just returns what it has handy at that point,
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# so we do to.
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data = None
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if not data:
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break
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ret.write(data)
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return ret.getvalue()
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def readinto(self, b):
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data = self.__read(len(b))
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n = len(data)
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try:
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b[:n] = data
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except TypeError as err:
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import array
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if not isinstance(b, array.array):
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raise err
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b[:n] = array.array(b'b', data)
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return n
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def write(self, b):
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if self._write_watcher is None:
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raise UnsupportedOperation('write')
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while True:
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try:
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return _write(self._fileno, b)
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except OSError as ex:
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if ex.args[0] not in ignored_errors:
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raise
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wait_on_watcher(self._write_watcher, None, None, self.hub)
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def seek(self, offset, whence=0):
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try:
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return os.lseek(self._fileno, offset, whence)
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except IOError: # pylint:disable=try-except-raise
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raise
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except OSError as ex: # pylint:disable=duplicate-except
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# Python 2.x
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# make sure on Python 2.x we raise an IOError
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# as documented for RawIOBase.
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# See https://github.com/gevent/gevent/issues/1323
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reraise(IOError, IOError(*ex.args), sys.exc_info()[2])
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def __repr__(self):
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return "<%s at 0x%x fileno=%s mode=%r>" % (
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type(self).__name__, id(self), self._fileno, self.mode
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)
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class GreenFileDescriptorIOWriteall(WriteIsWriteallMixin,
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GreenFileDescriptorIO):
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pass
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class GreenOpenDescriptor(OpenDescriptor):
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def _do_open_raw(self):
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if self.is_fd():
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fileio = GreenFileDescriptorIO(self._fobj, self, closefd=self.closefd)
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else:
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# Either an existing file object or a path string (which
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# we open to get a file object). In either case, the other object
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# owns the descriptor and we must not close it.
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closefd = False
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raw = OpenDescriptor._do_open_raw(self)
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fileno = raw.fileno()
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fileio = GreenFileDescriptorIO(fileno, self, closefd=closefd)
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fileio._keep_alive = raw
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# We can usually do better for a name, though.
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try:
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fileio.name = raw.name
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except AttributeError:
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del fileio.name
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return fileio
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def _make_atomic_write(self, result, raw):
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# Our return value from _do_open_raw is always a new
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# object that we own, so we're always free to change
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# the class.
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assert result is not raw or self._raw_object_is_new(raw)
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if result.__class__ is GreenFileDescriptorIO:
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result.__class__ = GreenFileDescriptorIOWriteall
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else:
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result = OpenDescriptor._make_atomic_write(self, result, raw)
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return result
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class FileObjectPosix(FileObjectBase):
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"""
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FileObjectPosix()
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A file-like object that operates on non-blocking files but
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provides a synchronous, cooperative interface.
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.. caution::
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This object is only effective wrapping files that can be used meaningfully
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with :func:`select.select` such as sockets and pipes.
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In general, on most platforms, operations on regular files
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(e.g., ``open('a_file.txt')``) are considered non-blocking
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already, even though they can take some time to complete as
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data is copied to the kernel and flushed to disk: this time
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is relatively bounded compared to sockets or pipes, though.
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A :func:`~os.read` or :func:`~os.write` call on such a file
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will still effectively block for some small period of time.
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Therefore, wrapping this class around a regular file is
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unlikely to make IO gevent-friendly: reading or writing large
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amounts of data could still block the event loop.
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If you'll be working with regular files and doing IO in large
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chunks, you may consider using
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:class:`~gevent.fileobject.FileObjectThread` or
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:func:`~gevent.os.tp_read` and :func:`~gevent.os.tp_write` to bypass this
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concern.
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.. tip::
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Although this object provides a :meth:`fileno` method and so
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can itself be passed to :func:`fcntl.fcntl`, setting the
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:data:`os.O_NONBLOCK` flag will have no effect (reads will
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still block the greenlet, although other greenlets can run).
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However, removing that flag *will cause this object to no
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longer be cooperative* (other greenlets will no longer run).
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You can use the internal ``fileio`` attribute of this object
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(a :class:`io.RawIOBase`) to perform non-blocking byte reads.
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Note, however, that once you begin directly using this
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attribute, the results from using methods of *this* object
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are undefined, especially in text mode. (See :issue:`222`.)
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.. versionchanged:: 1.1
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Now uses the :mod:`io` package internally. Under Python 2, previously
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used the undocumented class :class:`socket._fileobject`. This provides
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better file-like semantics (and portability to Python 3).
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.. versionchanged:: 1.2a1
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Document the ``fileio`` attribute for non-blocking reads.
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.. versionchanged:: 1.2a1
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A bufsize of 0 in write mode is no longer forced to be 1.
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Instead, the underlying buffer is flushed after every write
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operation to simulate a bufsize of 0. In gevent 1.0, a
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bufsize of 0 was flushed when a newline was written, while
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in gevent 1.1 it was flushed when more than one byte was
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written. Note that this may have performance impacts.
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.. versionchanged:: 1.3a1
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On Python 2, enabling universal newlines no longer forces unicode
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IO.
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.. versionchanged:: 1.5
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The default value for *mode* was changed from ``rb`` to ``r``. This is consistent
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with :func:`open`, :func:`io.open`, and :class:`~.FileObjectThread`, which is the
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default ``FileObject`` on some platforms.
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.. versionchanged:: 1.5
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Stop forcing buffering. Previously, given a ``buffering=0`` argument,
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*buffering* would be set to 1, and ``buffering=1`` would be forced to
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the default buffer size. This was a workaround for a long-standing concurrency
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issue. Now the *buffering* argument is interpreted as intended.
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"""
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default_bufsize = DEFAULT_BUFFER_SIZE
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def __init__(self, *args, **kwargs):
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descriptor = GreenOpenDescriptor(*args, **kwargs)
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FileObjectBase.__init__(self, descriptor)
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# This attribute is documented as available for non-blocking reads.
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self.fileio = descriptor.opened_raw()
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def _do_close(self, fobj, closefd):
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try:
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fobj.close()
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# self.fileio already knows whether or not to close the
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# file descriptor
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self.fileio.close()
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finally:
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self.fileio = None
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